1. Field of the Invention
The present invention generally relates to a compound semiconductor device and a method for controlling characteristics of the same, and more particularly, the present invention relates to a compound semiconductor device and a method for controlling characteristics of the same to obtain a homogeneous threshold voltage among plural transistors or a homogeneous resistivity among plural resistors.
This application is a counterpart of Japanese application Serial Number 073396/1997, filed Mar. 26, 1997, the subject matter of which is incorporated herein by reference.
2. Description of the Related Art
A conventional electronic component includes a plurality of field effect transistors and a plurality of resistors. The plurality of field effect transistors respectively have gates of different widths. Improved controllability of threshold voltages of the field effect transistors is important in stabilizing the performance of the electronic component.
The conventional method for controlling a threshold voltage of the field effect transistor is as follows:
First and second field effect transistors are simultaneously formed on the semiconductor chip. The second field effect transistor serves as a monitor for observing the process steps. That is, the threshold voltage of the second field effect transistor is measured after the ion-implantation for establishing a desired threshold voltage is completed. When the measured threshold voltage is lower than the desired value, the ion-implantation for establishing the desired threshold voltage is carried out for the second time.
An object of the present invention is to provide a compound semiconductor device that can precisely control a threshold voltage of a field effect transistor.
According to one aspect of the present invention, for achieving the above object, there is provided a compound semiconductor device comprising a first field effect transistor defining a first active region in a semi-insulating substrate, the first field effect transistor having a first ohmic source electrode and a first ohmic drain electrode extending over the first active region, a second field effect transistor defining a second active region in the semi-insulating substrate, the second field effect transistor having a second ohmic source electrode and a second ohmic drain electrode extending over the second active region, and wherein, a ratio of a difference between a surface area of the first active region and a combined surface area of the first source and drain ohmic electrodes to the combined surface area of the first source and drain ohmic electrodes is the same as a ratio of a difference between a surface area of the second active region and a combined surface area of the second source and drain ohmic electrodes to the combined surface area of the second source and drain ohmic electrodes.
An object of the present invention is to provide a compound semiconductor device that can precisely control a resistivity of the resistor.
According to one aspect of the present invention, for achieving the above object, there is provided a compound semiconductor device comprising a first resistor defining a first resistivity region in a semi-insulating substrate, the first resistor having a first pair electrodes extending over the first resistivity region, a second resistor defining a second resistivity region in the semi-insulating substrate, the second resistor having a second pair electrodes extending over the second resistivity region, and wherein, a ratio of a difference between a surface area of the first resistivity region and a combined surface area of the first electrodes to the combined surface area of the first electrodes is the same as a ratio of a difference between a surface area of the second resistivity region and a combined surface area of the second pair electrodes to the combined surface area of the second pair electrodes.
An object of the present invention is to provide a method for controlling a a characteristics of a compound semiconductor device that can satisfy homogeneity of the threshold voltages of the plurality of the field effect transistors at every substrate if a plurality of wafers treat using a single wafer processing.
According to one aspect of the present invention, for achieving the above object, there is provided a method for controlling a a characteristics of a compound semiconductor device comprising the steps of providing a first field effect transistor defining a first active region in a semi-insulating substrate, the first field effect transistor having a first ohmic source electrode and a first ohmic drain electrode extending over the first active region, a second field effect transistor defining a second active region in the semi-insulating substrate, the second field effect transistor having a second ohmic source electrode and a second ohmic drain electrode extending over the second active region, wherein, a ratio of a difference between a surface area of the first active region and a combined surface area of the first source and drain ohmic electrodes to the combined surface area of the first source and drain ohmic electrodes is the same as a ratio of a difference between a surface area of the second active region and a combined surface area of the second source and drain ohmic electrodes to the combined surface area of the second source and drain ohmic electrodes, measuring a threshold voltage of the second field effect transistor, and controlling a threshold voltage of the first field effect transistor based on the measured result.
According to another aspect of the present invention, for achieving the above object, there is provided a method for controlling a a characteristics of a compound semiconductor device comprising the steps of providing a first field effect transistor defining a first active region in a first semi-insulating substrate, the first field effect transistor having a first ohmic source electrode and a first ohmic drain electrode extending over the first active region, a second field effect transistor defining a second active region in a second semi-insulating substrate, the second field effect transistor having a second ohmic source electrode and a second ohmic drain electrode extending over the second active region, wherein, a ratio of a difference between a surface area of the first active region and a combined surface area of the first source and drain ohmic electrodes to the combined surface area of the first source and drain ohmic electrodes is the same as a ratio of a difference between a surface area of the second active region and a combined surface area of the second source and drain ohmic electrodes to the combined surface area of the second source and drain ohmic electrodes, measuring a threshold voltage of the second field effect transistor, and controlling a threshold voltage of the first field effect transistor based on the measured result.
An object of the present invention is to provide a method for controlling a a characteristics of a compound semiconductor device that can satisfy homogeneity of the resistivity of the plurality of the resistors at every substrate if a plurality of wafers treat using a single wafer processing.
According to one aspect of the present invention, for achieving the above object, there is provided a method for controlling a a characteristics of a compound semiconductor device comprising the steps of providing a first resistor defining a first resistivity region in a semi-insulating substrate, the first resistor having a first pair electrodes extending over the first resistivity region, a second resistor defining a second resistivity region in the semi-insulating substrate, the second resistor having a second pair electrodes extending over the second resistivity region, wherein, a ratio of a difference between a surface area of the first resistivity region and a combined surface area of the first electrodes to the combined surface area of the first electrodes is the same as a ratio of a difference between a surface area of the second resistivity region and a combined surface area of the second pair electrodes to the combined surface area of the second pair electrodes, measuring a resistivity of the second resistor, and controlling the resistivity of the first resistor based on the measured result.
According to another aspect of the present invention, for achieving the above object, there is provided a method for controlling a a characteristics of a compound semiconductor device comprising the steps of providing a first resistor defining a first resistivity region in a first semi-insulating substrate, the first resistor having a first pair electrodes extending over the first resistivity region, a second resistor defining a second resistivity region in a second semi-insulating substrate, the second resistor having a second pair electrodes extending over the second resistivity region, and wherein, a ratio of a difference between a surface area of the first resistivity region and a combined surface area of the first electrodes to the combined surface area of the first electrodes is the same as a ratio of a difference between a surface area of the second resistivity region and a combined surface area of the second pair electrodes to the combined surface area of the second pair electrodes, measuring a resistivity of the second resistor, and controlling the resistivity of the first resistor based on the measured result.